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From: Beman Dawes (beman_at_[hidden])
Date: 2000-06-05 19:06:16

At 06:39 PM 6/5/00 -0000, Miki Jovanovic wrote:

>--- In boost_at_[hidden], jsiek_at_l... wrote:
>> It seems to me that having all these operations
>> (read/write/add/test&set/exchange) is a bit overkill. What's wrong
>> with just a plain old mutex (with lock/unlock). Is there that
>> of a performance difference to be gained?
>Possibly. atomic_traits class is a set of utilities built on top of
>mutex. But this organization allows it to be optimised for
>> Oh, and along the lines of Steve's comment about signaling locks,
>> etc. the notions of a semaphore and of a condition variable (both
>> are in posix threads) are certainly important... probably
>> enough to be considered separately from mutexes.
>I strongly suggest we draw a line between basic promitives and
>extended synchronisation. Basic primitives should in my view include


  - thread?

> - mutex
> - signal
> - atomic_traits
>mutex and signal are absolutely the most basic primitives, and
>atomic_traits allow for optimisation of extended synchronisation
>Once we are happy with the basic primitives, then we can work on
>semaphores and conditinal variables. And the most beautiful part is
>that we will already have a standard library, because all of these
>extended classes can be implemented in terms of basic ones.
>If we keep it KISS, we will have a powerful foundation on top of
>which we can make a multithreading library as varied as we want.
>this make any sence?

It does to me. I'm plowing through a couple of books on threading,
and that seems to be the basic approach both authors take, too.

Incidently, getting these primitives right includes an error handling
strategy. The C++ Standard does not specify the operation of
exceptions across threads, so presumably exceptions can only be used
within a thread. Would a signal be a useful mechanism to report
errors across threads?


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